Understanding population social structure in group-living mammals provides a baseline for assessing environmental, social, and anthropogenic influences on social dynamics. This study presents the first broadscale examination of social association patterns, clustering, and temporal stability of Australian humpback dolphins (Sousa sahulensis) and Indo-Pacific bottlenose dolphins (Tursiops aduncus) across southeast Queensland, Australia. Association data from 263 individuals sighted at least five times between 2022–2025 were obtained via photo-identification surveys. Social network measures of gregariousness, half-weight indices, network characteristics, and community structure were examined across two regions: the Great Sandy Marine Park (GSMP) and Sunshine Coast (SC). Region exerted a stronger influence on social structure than species, with SC dolphins displaying significantly higher gregariousness, association strength, and connectivity compared to GSMP. Both species showed non-random preferred associations with no significant avoidance, though temporal stability differed: S. sahulensis showed rapid dissociation with casual acquaintances, while T. aduncus maintained preferred acquaintances over time. Moderate community structuring occurred in both species and regions, with complete social separation between regions. These findings demonstrate species-specific fission-fusion dynamics and establish a framework for monitoring how anthropogenic, demographic, environmental, and disease-related pressures may shape these populations.